1. Field of the Invention
The present invention relates to a polymeric composition useful as an electrical conduit covering, in particular, suited for vehicles.
2. Description of the Related Art
Recently, vehicle parts are highly required to be small-sized. An insulated electrical conduit for vehicles is also required to be small-sized.
However, it has been considered to be highly difficult to confer excellent flame retardant properties to an insulated electrical conduit for vehicle, with the insulated electrical conduit maintaining its small size. That is, conventional small-sized cable cannot achieve satisfactory flame retardant properties. Also, when a particulate inorganic flame retardant component such as magnesium hydroxide is added to a polymeric composition useful as an electrical conduit covering in a large amount, its flame retardant properties can be improved. However, in this case, its mechanical properties are inclined to be remarkably lowered.
To overcome the afore-mentioned problems, it has been proposed to substitute a part of magnesium hydroxide component with polyamide. By means of this solution, a resultant insulated electrical conduit could exhibit improved flame retardant properties while maintaining its original mechanical properties.
In addition, Japanese Patent Publication 2002-146118 (A) discloses a polymeric composition comprising an olefin polymer and a polyamide having relatively high melting point above 200° C. In this case, due to the addition of the polyamide component the composition can achieve improved heat resistance. However, due to addition of the polyamide component the polymeric composition has a melting point higher than that of conventional olefin-based composition. Accordingly, in its subsequent shape forming process, higher temperature would be applied thereto. The application of higher temperature may cause not only thermal degradation of the composition itself, but thermal degradation of the respective polymer component that comprises the polymeric composition. Furthermore, the material strength and abrasion resistance of the resultant article such as an insulated electrical conduit may be adversely affected.